Depression is an affectivity disorder in which a depressive syndrome is conspicuous, “depressive” being understood to refer to a state of dejection or melancholia. The antidepressants used for therapy are also important adjuvants for pain therapy (as is described in the publication by Tzschentke, Na and 5-hT Reuptake inhibitor and α2 agonists, in Analgesics: From Chemistry and Pharmacology to Clinical Application, Page 265-284, Wiley 2002), particularly in the case of chronic states of pain, since the continuous pain stress can cause a depressive mod in the patients. This is very frequently the case with cancer patients suffering pain (Berard, INT. MED—J. 1996, 3/4, 257-259). Treatment of depression is therefore highly significant in the field of medicine and there is a world-wide need for effective antidepressant therapies. The basis for such an antidepressant action in a pharmacological active substance is its capability to inhibit the reuptake of serotonin.